Method of Considering Equipment Constraints in a Manufacturing Planning System

1. In a manufacturing planning system for managing production of multiple lots of material where a manufacturing operation is to be performed at least twice on each lot of material, a method of accounting for manufacturing resource re-use constraints, the method comprising the steps of: assigning a first group of manufacturing resources to the operation which are each capable of performing the operation; assigning a second group of manufacturing resources to the operation which are each capable of performing the operation, each of the manufacturing resources of the second group having its re-use in performing the operation on a same lot of material constrained to ones of the lots of material requiring the operation to be performed with close tolerances; selecting one of the lots of material; wherein if the selected lot of material does not require the close tolerances, selecting one of the plurality of manufacturing resources from the first group for each performance of the operation; wherein if the selected lot of material requires the close tolerances, selecting one of the plurality of manufacturing resources from the second group for each performance of the operation.

2. The method according to claim 1 , wherein each resource comprises a different tool.

3. The method according to claim 2 , wherein the tool comprises photolithographic equipment.

4. The method according to claim 1 , wherein each resource comprises equipment.

5. The method according to claim 4 , wherein the equipment comprises photolithographic equipment.

6. The method according to claim 1 , further comprising the step of assigning the selected lot to the selected resource.

7. The method according to claim 6 , wherein the selected lot is assigned to the selected resource if predetermined loading balance and earliest finish time constraints are met.

8. The method according to claim 1 , wherein the second group of manufacturing resources is a subset of the first group of manufacturing resources.